Polyfunctional siloxanes containing terminal alkoxyl groups



3,175,993 PULYFUNCTEONAL STLOXANES CONTAINING TERMINAL ALKGXYL GROUPS Donmd R. Weyenherg, Midland, Mich, assignor to Dow Corning Corporation, Midland, Micln, a corporation of Michigan No Drawing. FiHedOct. 16, 1961, Ser. No. 145,442

7 Claims. (Cl. 26t)-46.5)

' This inventionrelates to organopolysiloxanes the molecules of which are endblocked with alkoxylated silcarbane groups. These polyfunctional polymers ,are capable of curing in air atroom temperature especially with certain catalysts. These polymers are especially useful for room temperature vulcanizing .elastomeric diorganopolysiloxanes.

The desirability of room temperature curing systems is now well established. Resinous systems are used primarily in coating applications such-as in wood lacquers.

.Elastorneric systems are used both in coating applications and in calking applications. The first room temperature curing systems involved two or more stable components which, when mixed together, cured spontaneously to some desired solid material. Such systems could not be marketed as one component systems due totheir spontaneous interaction resulting in curing the system to a solid, unworkable state.

Subsequently, it was found that certain fluid organopolysiloxanes containing silicon-bonded acyloxyl radicals as the only reactive groups were stablein the absence of moisture but cured in the presence of moisture to resinous or elastomeric solids depending on the organopolysiloxane structure and composition. it With present commercial materials the curing of thisone-component system is accompanied by the evolution of a carboxylic acid, generally acetic acid. This one-component system has been a great commercial success. Howeven there are some applications in which the presence of the carboxylic acid produced by this system is undesirable.

The desirability of a commercially competitive product having universal. application has made more urgent the perfection of other possible one-component room temperature curing .organonewone-component room temperature curing organopolysiloitane system whichis stable in the absence of moisture.

Another object is to provide such a system which is free of acid. Another object is to .provide a new. class of organopolysiloxane intermediates suitable for use in the new system. r

This invention relates to compositions of the average molecular formula Ilis lla-=- Si ()Si ZSKOR'); 4-y

in which each R is free of aliphatic unsaturation and is of the group monovalent hydrocarbon, monovalent halohydrocarbon and monovalent cyanoalkyl radicals of 1 to 18 inclusive carbon atoms, Z is a divalent hydrocarbon radical free of aliphatic unsaturation of from 2 to 18 inclusive carbon atoms. R is an alkyl radical or haloalkyl radical having no halogen alpha to the oxygen, both of United States Patent "cc 3,175,993 Patented Mar. 30, 1965 less than 5 carbon atoms, y has an average value from O to 2 inclusive, x has a value of at least 3 and a. has an average value from 2 to 3 inclusive.

The term average molecular formula means that the compositions of this invention include mixtures of the various configurations shown above and that in those cases where y is O or 1, the value of x in the various branches of the molecules can be of different values. The term also includes molecules in which some of the terminal OR groups have been hydrolyzed by the incidental presence of moisture during the preparation or storage of the compositions.

It can be seen that the characteristic feature of the above compositions is the presence of terminal silicon atoms having two or three alkoxy groups attached. This is the configuration whichimparts the distinctive. features described below to the compositions. It can also be seen that the molecules can be linear in structure having the configuration f the reaction of alkoxy groups with water andfor the I reaction of alkoxy groups with SiOH. However, the combination of catalysts and siloxane is stable in the absence of moisture. Therefore, they can be stored for prolonged periods of time. The term Fmoisture as used herein includes both water and water vapor including atmospheric moisture.

In the compositions of this invention, each R can be any monovalent hydrocarbon radical, any halogenated monovalent hydrocarbon radical or any cyanoalkyl radical. More specifically, each R can be, for example, any alkyl radical such as the methyl, ethyl, isopropyl, tert-butyl, 2-ethylhexyl, dodecyl, 1-isobutyl-3,5-dimethylhexyl, octadecyl and myricyl radicals; any cycloalkyl radical such as the cyclopentyl and cyclohexyl radicals; any aryl radicals such as the phenyl, naphthyl and xenyl radicals; any aralkyl radical such as the benzyl, phenylethyl and Xylyl radicalsand any alkaryl radical such as the tolyl and dirnethylphenyl radicals. These monovalent hydrocarbon radicals can be halogenated to give such radicals as the chloromethyl, 3,3,3-trifluoropropyl, 3,3,4,4,5,5,5-heptafluoropentyl, perchlorophenyl, -3,4 -dibromocyclohexyl, a,a,a-llifill0r0't0lyl, 2,4-dibromobenzyl and ocfifllrifllf0-oQQhlOIOCYClObll'EYl radicals, -all. of which are operative.

In addition each R can beany cyanoalkyl radical such as the beta-cyanoethyl, gamma-cyanopropyl, omegacyanobutyl, beta-cyanopropyl, gamma-cyanobutyl and omega-cyanooctadecyl. When a compound of this invention contains cyanoalkylradicalnit is preferred that such radicals be attached to at least one mol percent of the silicon atoms in the compound.

In the functional unitsin the compounds of this invention, each R in the functional. (R'O) groups can be any alkyl radical of less than about 5 carbon atoms, such as the methyl, ethyl, n-propyl and isopropyl radicals or any haloalkyl radical such as fl-chloroethyl, B-chloropropyl, 2,2,2-trifiuoroethyl, gamma-bromopropyl, deltav iodobutyl and 3,3,3,2,2-pentafluoropropyl. Preferably R is a methyl radical.

In the functional units in the compounds of this invention each Z can be any divalent hydrocarbon radical free of aliphatic unsaturation forming a' silcarbane linkage. Examples of suitable divalent hydrocarbon radicals include 00inch -cnMeorn with silanes of the formula il-a R"si(0R'),, in which R" is a monovalent hydrocarbon radical having an aliphatic or cycloaliphatic C=C group in the presence of a Pt catalyst. The reaction proceeds at temperatures of from to 150 C. with the addition of the silane to the SiH group to give the I v B-n -zsi(0R')..

group. Suitable catalysts for carrying out the addition are chloroplatinic acid, Pt on charcoal or Pt on alumina.

Alternatively one can react siloxanes of the formula Si[(OSi) XRQ with silanes of the formula v i-u *Hsnono, under the conditions shown above.

The intermediate siloxanes employed to make the compositions of this invention are made by conventional cohydrolysis of chlorosilanes of the formula R SiCI and R HSiCl or R R"SiCl. When y is 0 or 1, then SiCL; and/or RSiCl are included. The value of x is controlled by the mol ratio of the various silanes.

The unsaturated silanes employed herein are best prepared by the classical Grignard reaction between the magnesium derivative of an unsaturated halohydrocarbon and a chloroor alkoxysilane of the formula RSiX or SiX Suitable unsaturated hydrocarbon halides are CH =CHCI,, CHz CHCHzCl, Gino 01:01-12 GHmC CI CH added.

The unsaturated silanes in which R is a haloalkyl radical are prepared by reacting the halosilanes of the formula R"R SiX with halogenated alcohols or with 1,2 alkylene oxides. The reactions are desirable to employ a filler in order to extend the coma position or to impart specific properties thereto. Suitable fillers include organic compounds such as phthalocyanine, copper phthalocyanine and organic fibers and inorganic fillers such as metal oxides such as TiO zinc oxide, alumina, ferric oxide and magnesium oxide; siliceous materials such as aluminum silicate, clays and zirconium silicate; silicas such as diatomaceous earth,

sand, glass, powdered quartz, fume silica, silica aerogel and precipitated silica, powdered metals such as aluminum and zinc; and carbon such as graphite and carbon black.

As stated above, any catalyst which promotes the reaction of an alkoxysiloxane with Water or the reaction of an alkoxy group with a silanol group can be employed to cure the compositions of this invention in the presence of moisture. Preferably the catalyst should be compatible with the siloxane, although solvents can be 'employed, if desired, to increase the compatibility of the catalyst with the siloxane. Specific catalysts which are operative include organometallic compounds such as metal salts of monocarboxylic acids such as lead Z-ethylhexoate, dibutyltin diacetate, dibutyltin Z-ethylhexoalt, dibutyltin dilaurate, butyltin tri-Z-ethylhexoate, iron 2- ethylhexoate, cobalt 2-ethylhexoate, magnesium Z-ethylhexoate, zinc Z-ethylhexoate, stannous octoate, tin naphthenate, zirconium octoate, antimony octoate, bismuth naphthenate, tin oleate, tin butyrate, zinc naphthenate, zinc steara-te and titanium naphthenate; organotitanium esters and partial hydrolyzates thereof such as tctrabutyltitanate, tetra 2 ethylhexyltitanate, tetraphenyltitanate, tetraoctadecyltitanate, triethanolarninetitanate, octyleneglycoltitanate and bis-acetylacetonyl diisopropyltitanate; amines such as hexylamine, dodecylamine, di-n-hexylamine; amine salts such as hexylamine acetate, dodecylamine phosphate and hexylamine octoate; quaternary amine salts such as benzyltri-methylammoniumacetate, hydroxyethyltn'methylammonium -,2 ethylhexoate and tetraethylammoniumbutyrate; carboxylic acids such as acetic acid and formic acid and inorganic acids such as HCI.

For the purpose of this invention the amount of catalyst is not critical but it is normally present in amount of from .1 to 2 percent by weight, based on the Weight of the siloxane. V

The following examples are illustrative only and should not be construed as limiting the invention. The term Me is used herein as an abbreviation for the methyl radical.

EXAMPLE 1 the mixture as a soluble platinum compound, e.g. chl0ro-' platinic acid, and the system was heated to to C. The remainder of the reactant mixture was then The system was heated one hour at C. and

KA R M "A mixture of 265.5 grams of (A) in Example-1, 53

grams of vinylmethyldimethoxysilane and approximately --parts by weight'per million of platinurri'ba'sed'on the total reactants 'added as ai'solution of'a soluble platinum compound, e.g., chloroplatinic acid, in ethanol was refluxed for about two hours. Another 15 grams of vinylmethyldimethoxysilane with another portion of platinum catalyst were then added .to the reaction mixture. The resulting mixture was heated for 2 hours at 170 .to 18() C. and stripped to 150 C. at 2 mm. Hg, yielding a clear straw colored fluid of the general formula (CH O) Si (CH CH CH Si(CH 0 [Si (CH 0] n Si(CH CH CH Si(CH (OCH 2 in which n has an average value of about 21. 20 grams of this product were mixed with about 0.25 gram of stannous octoate. A portion of this sample was placed in an open dish. This portion had a tack-free solid sur- 6 face film in minutes. and. was complet'ely .cured in 72 hours Theremai nde bottle showed no. change Two mixtures were prepared. Theifirst was made up of 10 grams of la siloxane like; that produced in Example 1 and about Q.1 gram of tetraisopropyltitanatet. The second w ama efiw il l of t x e d" prodnoedin Exan pleZ'and about 0.1 grarrr -of tetraisopro Both mixtures cured to tack-free solid films in less than 24 hours in air at room temperature. There was no change during this time in portions of these mixtures kept in closed bottles.

About 0.1 gram of tetrakis-methylcellosolve-titanate was added to 8 grams of the siloxane fluid. producedin Example 2. A portion of this mixture cured in thin secti'on;to -a tack-free; filnrin 48 hours in air at room tem perature.

EXAMPLE 5 The following alkoxyl-ated siloxanes are obtained when the following siloxanes are reacted with the following sil-anes in the presence of the catalysts of Example l r of the mixture storedin .a capped When each of the above alkoxysiloxanes is mixed with stannous octoate in amount of 1 percent by weight based on the weight of the siloxane, the resulting product is stable in the absence of moisture but will cure on exposure to the atmosphere. 5

EXAMPLE 6 When the following halosilanes are reacted with the following alkylene oxides, the following silanes are obtained. The reaction is carried out at room temperature by adding the oxide to the chlorosilane with stirring. 10

Alkylene oxide Halosilane Silane CzHaSlCl; Ethylene oxide CH3S1(O CH CHzODa Br CHz=CHCHzSiBr3 1,2-pr0pylene oxide CHFOHCH Si(OCHz( lHCH3)3 Me Me 01 C H S i0h 1,2-butylene oxide.-. O HgSKO CH2 C I'HC1H When the following alcohols are reacted with the following chlorosilanes, the following silanes are obtained.

free of aliphatic unsaturation of from 2 to 18 inclusive carbon atoms, R is selected from the group consisting Chlorosil'ane Alcohol Silane C H SiCl CFQlCEZOH CgH3Si(OCHzCFa)3 06m can CzH3S iOlz CH2C1CH2CH2OH OzH3Si(OCH2CHzCHzC1)z CzHaSiCla CHgOKCHQsQH CzHaSi[O(CH2)3CHzCl]3 CH 7 CHE-o1 CzHgSiCla CICHK JHOH C2H3Si(OCHCH When each of these siloxanes is mixed with .3 percent by weight dibutyl tin dilaurate in the absence of moisture the composition is stable but they will cure to rubbery materials on exposure to moisture. 7

of haloalkyl radicals having no halogen alpha to the oxygen and alkyl radicals, both of less than 5 carbon atoms, y has an average value from 0 to 2 inclusive, x has a value of at least 3 and a has an average value from 2 to 3 inclusive.

2. A composition in accordance with claim 1 in which R and R are both methyl and in which Z is an ethylene group.

3. A curable benzene soluble composition of matter which is stable in the absence of moisture but cures at room temperature on exposure to moisture consisting essentially of (1) a siloxane of the average molecular formula Si[(OSi)xZSi(OR')n]l-y in which each R is free of aliphatic unsaturation and is selected from the group consisting of monovalent hydrocarbon radicals, monovalent halohydrooarbon radicals and monovalent cyanoalkyl radicals, all of froml to 18 inclusive carbon atoms, Z is a divalent hydrocarbon radical free of aliphatic unsaturation, all of from 2 to 18 in- 9 l0 5. A composition in accordance with claim 3 in which FOREIGN PATENTS both R and R are methyl radicals. 508,113 12/54 Canada 6. The method comprising exposing the composition of 865,658 7 /49 Germany claim 3 to moisture whereby said composition is cured.

7. The method comprising exposing the composition of 5 OTHER REFERENCES claim 4 to moisture whereby said composition is cured. Eaborn: Organosilicon Compounds (N.Y.: Academic Press, Inc., 1960), page 469. References Clted by the Examlllel Titanium and Latex, Paint, Oil and Chemical Review,

UNITED STATES PATENTS March 2 1 pages 2,562,000 7/51 Sveda 260-465 10 2,590,937 452 Clark 26046.5 MURRAY TILLMAN,Pr1mary Examzner.

3 122 522 2 4 Brown et 1 2 0' 44g 3 J. R. LIBERMAN, WILLIAM H. SHORT, Examiners. 

1. A COMPOSITION OF MATTER CONSISTING ESSENTIALLY OF MOLECULES OF THE AVERAGE FORMULA
 3. A CURABLE BENZENE SOLUBLE COMPOSITION OF MATTER WHICH IS STABLE IN THE ABSENCE OF MOISTURE BUT CURES AT ROOM TEMPERATURE ON EXPOSURE TO MOISTURE CONSISTING ESSENTIALLY OF (1) A SILOXANE OF THE AVERAGE MOLECULAR FORMULA 